High power discharge device



Aug- 27, 1940' J. E. CLARK ET AL.

HIGH POWER DISCHARGE DEVICE Filed June 1, 1938 4 Sheets-Sheet 1 J.ECLARK lNl/ENTORS: 5.0.E/(STR14ND By I. RONC/ A TTORNEV Aug. 27, 1940.

J. CLARK ET AL HIGH POWER DISCHARGE DEVICE Filed June 1, 1938 4Sheets-Sheet 2 JECLARK IN VENTORS 5.0.E/(5 TRAND By MLRONC/ Wallis, (57M A TTOR/VEV Aug. 27, 1940.

' J. E. CLARK ET AL HIGH POWER DISCHARGE DEVICE Filed June 1, 1958 4Sheets$heet 5 J. E. CLARK v MLRONC/ A T TO/PNEV Patented Aug. 27, 1940entries stares 2,212,929 HIGH rowan DISCHARGE nnvror.

James-1E.- Clark, Long Island City, N. Y, Stare 0. Ekstrand,lB-ergenfield, N. 5., and, Victor L. Ronci, Brooklyn, N. iZ., assigncrsto Bell Telephone Laboratories, Incorporated, New York, N.Y., acorporation of New York Application .i'une l, 1938, Serial No. 211,184

15 Claims.

This invention relates to improvements in space current devices and moreparticularly to devices for controlling a large amount of power.

In such devices, especially of considerable size and capacity, forinstance, devices having a rating of 250 kilowatts or more, it isessential to provide high insulation resistancebetween the low potentialelectrodes such as a cathode and a grid or control electrode and a highvoltage anode. Furthermore, under the high temperature conditionsprevalent during operation, electrostatic stresses and mechanicalstrains must be minimized to insure a high power output efiiciency. Itis also desirable to maintain the cathode under tension to compensatefor electrodynamic forces tending to distort the cathode strands andthereby alter the operating characteristics of the device. Under. theseconditions frictional resistance between cooperating elements of theelectrode supporting assemblies must be reduced to insure long operatinglife and stable spaced relationship between the active electrodesurfaces.

An object of this invention is to facilitate the assembly of the variouselectrodes in a device to insure high power efficiency and highinsulation resistance between the electrodes.

Another object of the invention is to preserve the inter-spacialrelationship between the several electrodes regardless of the intenseheat generated in the device.

A further object of the invention is to alleviate.

frictional, electrostatic and electrodynamic forces which producetorsional strains and distort the internal electrodes.

It is also an object of the invention to organize the assembly of thedevice in such a manner that the various electrodes may be fabricatedinto a compact unit of high power rating with a minimum of skilled laborand at a low cost commensurate with the power capacity.

In accordance with the general aspects of this invention, the high powerspace current device is particularly applicable to the external metallicanode type in which the anode forms a part of the enclosing vessel andthe heat generated in the anode is dissipated by a cooling fiuid flowingin a jacket surrounding the anode. The anode is provided with a hollowinsulating portion at each end to support the internal electrodes, suchas a cathode and a grid, in uniform coaxial relation to the anode and toprovide long insulating paths between these electrodes and the highpotential anode. The filamentary cathode assembly is mounted coaxiallywithin the anode by the end insulating portions and a control elec- Itrode or grid is interposed between the cathode and the anode and isalso supported at both ends by the insulating portions. This arrangementinsures a compact unit inwhich the interspacial relationship of theelements is accurately maintained and a large amount of power isgenerated and controlled with high emciency. Furthermore, the usefullife of the device is materially increased by the high leakageresistance paths between the electrodes. i

A feature of this construction, particularly for multi-phase powersupply for heating the cathode to its operating temperature for maximumspace current conduction in the device, is the distribution of theleading-in conductors in spaced relation in onset the hollow insulatingportions and the cooperative tension assembly for the cathode in theopposite insulating portion sothat the multiple strands ofthe cathodeextending through the anodeportion are uniformly spaced with respect tothe anode surface.

A further feature of the above assembly is the substantially completeshielding of the ten sion assembly for the cathode from the hightemperature zone of the device. This is accomplished by providing aninner insulating chamber within one of the hollow insulating endportions of the device and mounting the tension assembly therein so.that it is substantially unaffected by the intense heat generated duringoperation, thereby materially increasing the operating life of thedevice.

Another feature of this invention relates to the alignment of thestrands of the cathode by a guiding assembly which insures accuratelinearity of the strands with their rigid terminal ends to avoid strainon theseals of the leading-in conductors. This arrangement embodiesrigid guid-. ing mounts adjacent opposite ends of the multistrandcathode having jewel bearings for the conductorsand tension hangers forthe cathode assembly. These guiding mounts insure the lowest coeificientof friction at high temperatures and thereby insure the proper tensionin the 45 filament strands to compensate for the electrodynamic forcesexerted on the strands during I operation. 1

A further feature of the'tension assembly of. the cathode strands is theaxial relationship of the tension springs and hangers for the filamentstrands whereby the tension force is applied along the axis of thehangers. This is accomplished by placing a spring around each hanger andsecuring the hanger to the spring by a gripping 55 v rigid pins fixed inthe seating member.

mechanism which permits the hanger to ride freely in the guide mountalong a normal line of low frictional resistance.

An added feature of this assembly is the adjustable mechanism forapplying a uniform tension to all the filament strands and the positivelocking arrangement for maintaining the required tension on the filamentstrands. This assembly involves a common adjustable member mounted inone end of the inner chamber of the device which is connected to aplatform carrying all the tension spring units. After the proper tensionis applied, the adjustment is locked in a sleeve extension on thechamber closure. This arrangement also facilitates assembly andadjustment of the tension mechanism after the filament hangers arefabricated in the chamber.

The hanger gripping mechanism also constitutes another feature of thisinvention whereby the filament hangers are secured to the tension springunits. This construction comprises a gripping chuck which securelyembraces the filament hanger and prevents slippage of the hanger inalongitudinal direction. The chuck includes an insulating sleeveadjacent to the chuck jaws to.

insulate the individual strands and the chuck jaws are reenforced by anauxiliary member of high tensile strength to prevent deformation of thejaws due to the tension stress placed upon the hanger.

Another feature of the tension assembly involves the location of thespring units between the top and bottom guide mounts to relievetorsional strain on the springs during transitional periods of expansionand contraction incident to the operation of the device.

Several features of the invention are embodied in the grid assembly toinsure coaxial and angular relationship of the controlling portion ofthe grid with the cathode strands and the surface of the anode.

The grid structure is provided with guide extensions which are capableof moving in low friction bearings mounted in an annular ring memberformed on one of the hollow end portions of the deviceto permit the gridto expand and contract without distortion. This arrangement also permitsa limited lateral movement of the grid guides and thebearings duringexpansion periods to prevent torsional strain affecting the contour andalignment of the grid structure.

Another feature of the grid assembly is the mounting of the opposite endof the grid on an annular seating member carried by the opposite endinsulating portion of the device. In this construction the gridsupporting rods are attached to segmental connectors which are afi'ixedto the annular seating member at their centers by These pins extendthrough the connectors and press against tension strips to compensatefor differences in planar relations between the grid supports and theseating member. This arrangement facilitates assembly since it isunnecessary to provide precision alignment of the grid supports withdefinite apertures in the seating member and limits strains set up bydifferential expansion of the elements.

The invention, both as to its organization and method of assembly, withfurther features and advantages will best be understood by reference tothe following detailed description in combination with the accompanyingdrawings showing the preferred embodiment of the device.

' Fig. 1-is a general perspective view of the complete device embodyingthe features of this invention;

Fig. 2 illustrates a straight-line assembly of the principal elements ofthe cathode supporting structure in the same relation as shown in thedevice of Fig. 1;

Fig. 3 is an enlarged View of the lower portion of the cathode structureof Fig. 2 with parts in cross-section to show details of the assembly;

Fig. 4 is an enlarged view of the upper portion of the cathode structureof Fig. 2 with certain parts shown in cross-section;

Fig. 5 is an enlarged view of the grid structure employed in the deviceof Fig. 1 with essential parts of the supporting structure shown tovisualize the assembly;

Fig. 6 shows a perspective view of the top mounting stem for the grid ofFig. 5;

Fig. '7 shows a perspective view of the bottom mounting stem for thegrid of Fig. 5;

Fig. 8 is an exploded view in perspective of the stem and associatedparts shown in Fig. 7;

Fig. 9 is an enlarged view in partial cross-section showing the assemblydetails of the tension unit for the cathode;

Fig, 10 is a further enlarged cross-sectional view of one of the springtension units shown in Fig. 9;

Fig. 11 is a plan view of the details of Fig. 9 taken on the line I 1-!l; and

Fig. 12 is a pla n view of the assembly taken on the line l2l2 of Fig.9.

Reference will now be made to the drawings and particularly to Fig. 1,showing the complete assembly, which has an over-all length ofapproximately seven feet and a capacity of 250 kilowatts power output.The device involves a highly evacuated enclosing vessel of the generalform shown in U. S. Patent 1,976,521, issued October 9, 1934, to V. L.Ronci and J. E. Clark. This vessel includes a cylindrical metallic anodeportion 26, preferably of copper, surrounded by an integral metalliccooling jacket 2! and two vitreous bulbous end portions 22 and 23, ofrelatively hard boro-silicate glass, which are hermetically sealed tothe opposite ends of the anode portion in accordance with the methoddisclosed in U. S. Patent 1,294,466, issued February 18, 1919, to W. G.Housekeeper. The cooling jacket 2i is preferably formed of two halfsections, for convenience of manufacture, which are joined together atthe center by a ring member 24 brazed over the abutting ends of the halfsections and the extreme ends of the jacket are brazed to the wall ofthe anode portion 29. The whole external surface of the water jacket andthe projecting ends of the anode are coated with a protective layer ofoxidized silver to prevent deleterious oxide formation and also toimprove the physical appearance of the metal parts of the device.

The bulbous end portion 23 is provided with a reentrant tubular glassportion or sleeve 25 having a flare 26 fused to the open end of theportion 23. A precast or molded dish-type stem 27 shown more clearly inFig. 3 is provided with six tubular sleeves or ferrules 28 arranged incircular formation'and projecting outwardly toward the joined ends ofthe tubular portion 25 and the end portion 23. The stem 21 has a flangedrim 29 which is fused to the inner wall of the tubular portion 25,adjacent the inner end thereof. The stem 2'! is also provided with acentral integral tubular extension 39 which projects to wards the anode26 and is coaxially arranged through clearance holes in the shield 36.

with respect to the axis of the device. A metallic collaror sleeve 3|,preferably of copper, is sealed into the end of the tubular extension 3Band forms, a supporting base for a guiding mount. This mount consists ofa plurality of steel spindles 32 attached to a supporting plate 33 whichis securely fastened in the collar or sleeve iii. The spindles carry apair of spaced guide plates 3t and $5 and the mount also supports ametallic shielding disc 36 adjacent the top guide plate 35. The steelspindles provide a rigid supporting structure for the guide plates andare protected against serious corrosions by nickel sleeves 4 3 betweenthe plates 33, 34 and 35 of the mount.

Each of the ferrules 28 in the stem 2 has a metallic cup 31 hermeticallysealed to the rim of the ferrule to form the conductor seals forsupplying heating energy to the cathode of the device. A flexible heavyconductor 38 is brazed to the outer end of the cup 3'! and a compositeconductor is connected to the interior of the cup 3?. This conductorconsists of a length of copper rod 39 brazed at one end in the interiorof the cup ill and extends vertically beyond the collar H. A tungstenrod section ill extending into a counter-bored end of the copper rod 39is bent inwardly above the joint to extend through guide holes in theplates 35 and 35 and also extends Beyond the shield 36 the rod all isjoined to a counter-bored molybdenum section 42 which is provided with areduced end portion 33. the composite conductors are arranged on theboundary of a cylinder and therefore surround the guide mount supportingcollar 3! with the tungsten sections 48 bent inwardly to pass throughthe guide apertures in parallel relation in the plates and 5-25. Thearrangement of the conductors insures a structure which is free fromsubsequent mechanical defects since the bend in the conductors isprovided in the tungsten section it which does not develop fatiguestress and the molybdenum section 42 and the copper'section 39 are freefrom bends so that no mechanical stresses can develop in the conductors.electron emitting cathode formed of a plurality of loop strands 45,preferably of tungsten, have their parallel ends fused or welded intothe reduced end it of the molybdenum section of the conductors.

The glass end portion 22 on the opposite end of the anode 2B isprovided-with a sealed tip it through which the device is exhaustedprior. to the sealing operation. An annular sleeve El, of glass, havinga flare portion 38 sealed to the inner wall of the end portion 22intermediate the tip and the anode 29, extends in adirection toward thetip with the rim thereof fused to the flares of the two cylindricalglass members 49 and 5i. so that the cylinder 49 extends toward the tipas while the cylinder 5% extends toward the anode and together form aninner chamber El. The sleeve M is also provided with a plurality ofports 52 as shown in Fig. 4 which form outlets for gases and vaporsgenerated by the electrodes during the evacuation process which arepumped out through the spaceleading to the tip 4% of the device.

All of within the area of the anode proper and therefore forms anenclosure which is substantially unaffected by heat radiation orconduction in the device. Furthermore, the chamber being substantiallyformed of vitreous insulating material the mass of the structure ismaterially reduced and there is less'chance for the chamber structure tobe impaired by high frequency heating usually employed in degassing someof the internal electrodes and elements of the device. However, thechamber may also be formed of a metal wall in devices of lower capacitywhere the change is desirable for manufacturing reasons,

vA. central spindle 58 is secured to the closure disc or' plate 5? andextends downwardly in the direction of the anode and is coaxialtherewith. A guiding plate 59 is secured to the end of the, spindle anda metallic shield 65 is arranged across the face of the guiding plateand attached to the center thereof. pended from the lower closure plate5? carries a plurality'of verticalsteel rods M which extend through theclosure plate Eel and support a second guiding plate 62 having acylindrical sleeve 63 projecting through an aperture in the closureplate Eiii. This arrangement insures an axial alignment of the bearingmount since the guiding sleeve 63- cooperates with a central opening inthe top closure plate to align the apertures in the guide plates 59 and62 forreceiving a plurality of rigid hanger rods 54, preferably oftungsten, which extend successively through the top closure plate 56,guiding plate 62, closure plate 51, guiding plate 59 and shield lit. Theend of the hanger rod within the anode area is provided with a curvedshield member t5 having a rigid sheave 66 attached to the inner surfacethereof The guiding mount sus-.

to receive a loop end of the cathode strand 6%. A

helically wound wire sleeve 67 surrounding the filament strand is seatedover the sheave and the wire sleeve is provided with an eccentric loop68 at the center thereof which is seated in a slot 8Q of the sheave andsecured thereto by a tie wire l0 which passes through the eccentric loopand is threaded through small holes in the bottom of the sheave. Thisarrangement prevents the sleeve 671 being displaced from the sheave andalso prevents the filament strand from being displaced from the sheaverace. However, the filament strands may move through the sleeve t'idepending on the expansion and contraction of the parallel strands ofthe filament without any danger of the filament being welded to thesheave 6% when it is heated to operating temperature.

The hangers 64 are resiliently supported by a tension assembly or unitmounted within the inner chamber 5!. The tension assembly includes anadjustable tension member or screw l l, which extends through theguiding plate 62 and carries a threaded platform 52 slidably centered onthe rods iii. The platform also carries a plurab ity of helical tensionsprings l3 which surround the hanger members 55 and sup-port grippingunits or chucks M which frictionally engage the hanger rods 64. Theadjustable screw H is locked in position after the proper tension isapplied to the hanger members by a set screw which is also looked inposition by a slot 15 in the guiding sleeve 63. This arrangementprovides a tension support for the filament strands in which the tensionforces are applied to the hangers along lines parallel with the axis ofthe device and strains caused by electrodynamicforces acting on theheated filament strands are minimized to ensure freedom from mechanicalfaults.

The control electrode or grid assembly and the details thereof are shownclearly in Figs. 5 to 8, inclusive. This assembly embodies a supportingstructure in each of the end glass portions 22 and 23 which includes anannular dish-type glassmounting or stem 16 fused to the inner wall ofthe glass end portion 22 adjacent the lower end of the inner chamber 5!with its smaller diameter end projecting toward the anode 20. A similarannular dish-type mounting or stem H is fused to the inner wall of theend portion 23 just beyond the position of the metallic sleeve 3!supporting the guiding mount for the filament. This stem also has itssmaller diameter end projected toward the anode 2E]. The shape of thisannular support is shown more clearly in Fig. 6 in which the largerdiameter end is provided with a flange rim 78 which is sealed to thewall of the end portion. The smaller diameter end of the support hasthree equaly spaced depressed sides so that the aperture forms anoutline of a clover leaf, the subtended portions being provided withbearing seats 19.

The grid assembly is composed of vertical spaced rods 36 which support ahelical winding 8| which forms the grid proper and is located betweenthe cathode 45 and the anode 2B in coaxial relation thereto. The gridsupporting rods 86 are attached to end collar members 82 and 83 whichalso carry rod extensions 8 1 and 85, respectively, projecting inopposite directions from the grid proper. These rods are reenforced byadditional collars 86 and Bl, respectively, which are provided with bentportions which clear the bearing projections l9 on the glass supportingstems l6 and H. Three of the rods 84 at spaced positions on the collar36 project beyond the collar and are connected to tungsten guide rods 88by molybdenum sleeves 89. The guide rods 88 pass slidably through asynthetic jewel bearing 98 enclosed in a bearing seat formed in theportion "#9. Glass beads are fused over the seat opening and thebearings are retained within the seat although the bearing is free forlimited movement within the seat in all directions. These bearings areformed of highly fused aluminum oxide which has been subjected to suchhigh temperatures that the bearing exhibits characteristics of asapphire of commercial grade having a very low coeiiicient of frictionat the temperatures encountered during the manufacture and use of thedevice. Other suitable bearing material may be employed having the aboveproperties. The bearings may be completely polished although it is onlynecessary to polish the inner surface thereof to provide a low frictionsurface for the guide rods 88.

The supporting rods 85 of the grid structure extending beyond the ring81 are connected in pairs to arcuate metal members by a threadedconnection and the members are secured to the annular support ll atsuitable bearing points.

.The grid structure is supplied with controlling current through anexternal terminal 52 sealed to the side wall of the end portion 28 andthis terminal carries an inner metallic plug 93 which is provided with aflattened end to be secured to a bifurcated flexible conductor 94 havingthree arms which are connected to the arcuate members supporting thegrid structure. A metallic base 95 is also attached to the end glassportion 23 and carries a number of metallic bushings 96 for theleading-in conductors 3B which are provided with terminal lugs 9iexterior to the device. The base isprovided with apertures forcirculating air through the hollow cavity en closing the terminal seals31 of the conductors and these apertures are arranged in the base sothat an air hose 98 may be threaded to a central nipple 99 on the baseto inject air into the seal chamber. A ring of outlet holes I00 isprovided around the bushings 96 in the base as outlet ports for the air.

In addition to the jewel bearings 90 for providing a low frictionsliding support for the grid structure, similar bearings ml, as shown inFig. 9, are also provided in the bearing plates 34, 35, 5t and 62 forthe cathode assembly so that the current conductors are free to expandin a longitudinal direction with the least amount of friction and thecathode hangers 6 3 may be slidably movable in normal planes to thecathode strands. The details of the bearing plate in the guide mount areshown in Fig. 9 and a description of one of the plates 62 will sufficefor the remaining guide plates associated with the cathode structure.The main bearing plate is a disc, such as 52, having apertures Hi2slightly larger in diameter than the jewelbearing H3! so that thebearing has a limited movement in the bearing plate. The bearings areheld in position by end cover plates I03 and H1 5. While all the bearingplates are substantially the same in general structure and form, theupper bearing plate 62 has a configuration in which the bearings arelocated in three arms of the plate as shown in Fig. 11. The bearingplate 52 also carries the guiding sleeve 63 for aligning the guidingmount for the hangers 64. Figs. 9 and 11 also show the closure plate 56provided with three holes or apertures N35 to provide clearances to thelock nuts I86 for attaching the lower closure plate 57 to a backing ringlil'i which is fastened to the collar 5%. These apertures permit a toolto be inserted into the chamber 5! to lock the nut H16 in position. Thecut-out portions of the three-armed plate 52 provide clearances for thetool. I

The bearing plate 62 also forms a mounting for the adjustable tensionscrew ll which is threaded to the tension platform 12. The tension isapplied to this screw by a special tool which is inserted in the holesI08 in the head $09 of the screw and the tension is maintained by aset-screw Hil which is locked in the slot 15 of the guiding sleeve 63.

The tension platform 12 carries three gripping sleeves or members formedof a two-part coupling composed of an internal sleeve 1 l I threaded atboth ends having a central aperture for the passage of the hanger 6 1and an external member H2 internally threaded for gripping the end turnsof the tension spring '13 as shown in Fig. 10. The friction chuck M onthe opposite end of the tension spring E3 is composed of a sleevecoupling having an inner member H3 and an outer member H4 gripping theopposite end of the tension spring 13 and the outer member is threadedto a chuck body H5 which encloses a pair of split jaws H6 havingsemicircular ridges I H reenforced by a backing piece of molybdenum rodH8, the ridges Ill fitting into a detent H9 on the hanger 64. Aninsulating sleeve I20 is mounted in the chuck between the split jaws andthe body member H5, to insulate each hanger in the tension assembly anda spacer sleeve l2| separates the split jaws from the insulator as shownin Fig. 10.

The tension mounting of the grid assembly as shown in Figs. 7 and 8facilitates the fabrica- 1'5 nectors are tion of the grid structure inthe device and provides a support in which differences in alignment ofthe grid rods and the supporting stem are compensated and precisioncouplingis eliminated by providing pin bearings for connecting the lowerend of the grid to the supporting stem. As shown in Fig. 8 the threebearing seats 19 have individual pins i22 sealed therein and these pinsextend beyond the surfaces of the bearing seats to form pivots whichenter the central apertures of a pair of arcuate connectors I23 and i2 3located above and below the bearing seat lid as shown in Fig. 7. Theseconnectors are provided with a central cut-out portion so that the endsare in'abutting relation and clear the depth of the bearing seat 79 inthe stem ii. A pair of resilient metallic springs H5 and I26, preferably01" molybdenum, having the same contour as the connectors lie over theouter faces of the connectors. These springs and the associatedconnectors are drilled at the ends to receive a pair of threaded rods 85of the grid structure so that each pair of rods is attached to anindividual arcuate connector or segmental ring and the centersoftheconnectors are coupled to the pins 22 in the stem for supporting thegrid.

When the associated nuts are applied to the grid supports 85 extendingthrough the lower connectors and springs, the associated pair. ofcondrawn together and the pin bears against the resilient spring toapply a tension force to the mounting and thereby securely fasten thegrid structure to the stem.

The combined units as heretofore described produce an assembly in whichhigh efiiciency may be obtained from the device with a minimum ofmechanical defects even at high temperatures. The assembly also insureslong operating life for a high power device by providing an organizationwhich compensates for electrodynamic and electrostatic forces anddifferential expansion present in the device under high power operatingconditions.

While the various structures have been described in connection with aspecific embodiment of the invention, it is, of course, understood thatvarious modifications may be made in the detailed assembly and theassociation of the related parts without departing from the scope ofthis invention as defined in the appended claims.

What is claimed is:

, l. A discharge device including a metallic anode portion, vitreousportions sealed to opposite ends of the anode portion, a filamentsupporting assembly in said device including a plurality of filamentstrands, terminal conductors attached to said strands and extendingthrough one of said vitreous portions, and a tension assembly for saidstrand enclosed in the other vitreous portion, said assembly comprisinghanger members, a plurality of guiding means for said members, andspring tensioned elements for said members between said guiding means.

2. A high power discharge device having a metallic anode portion and ahollow glass portion sealed-thereto, a multistrand filamentwithin saidanode portion, a plurality of hangers for said multistrand filament, aninsulating chamber portion within said glass portion, a tensionsupporting assembly for said hangers mounted in said chamber, and meansincluding said chamber portion protecting said assembly from radiationof heat generated in the high temperature region of said anode portion.

3. A high power space current device having a cylindrical metallic anodeportion terminated by end insulating portions, a plurality of leading-inconductors sealed into one of said insulating portions and extendinginto said anode portion, a plurality of electron producing strandsjoined to said conductors and extending through said anode portion incoaxial relation thereto, a hollow chamber portion mounted within theother insulating portion, metallic closure mem bers for the oppositeends of said chamber, parallel hanger members passing through saidclosure members and extending into said anode portion to support saidstrands, and a tension unit mounted in said chamber, said unit includingspring assemblies individually surrounding and irictionally embracingsaid hangers to apply tension force to said strands.

i. A high power space current device'having a cylindrical metallic anodeportion terminated by end insulating portions, a plurality of leadinginconductors sealed into one of said insulating portions and extendinginto said anode portion, a plurality of electron producing strandsjoined to said conductors and extending through said anode portion incoaxial relation thereto, a hollow chamber mounted within the otherinsulating portion, a metallic closure member for each end of saidchamber, parallel hanger members passing through said closure membersand ex tending into said anode portion to support said strands, ametallic guide plate adjacent each of said closure members, a supportfor each plate engaging its respective closure member, a plurality ofbearing elements of low frictional coefficient at high temperatureslocated in each guide plate, said hangers slidably engaging said bearing1 elements, and ,a tension unit for said hangers positioned within saidchamber between a guide plate and one of said closure members.

5. A high power spaced current device having a cylindrical metallicanode portion terminated by end insulating portions, a. plurality ofleadi jin conductors sealed into one of said insulating portions andextending into said anode portion, a plurality of electron producingstrands joined to said conductors and extending through said anodeportion in coaxial relation thereto, a hollow chamber mounted within theother insulating portion, metallic closure members for the opposite endsof said chamber, parallel hanger members passing through said closuremembers and extending into said anode portion to support said strands,and a tension unit mounted in said chamber, said unit including aplatform and sprin assemblies surroundin said hangers, a guiding plateadjacent said tension unit having a tubular sleeve extending through oneof said closure members, and a tension adjusting element within saidsleeve and engaging said platform.

6. A high power space current device having a cylindrical metallic anodeportion terminated by end insulating portions, a plurality of leading-inconductors sealed into one of said insulating portions and extendinginto said anode portion, a plurality of electron producing strandsjoined to said conductors and extending through said anode portion incoaxial relation thereto, a hollow chamber mounted within the otherinsulating portions, metallic closure members for the opposite ends ofsaid chamber, parallel hanger members passing through said closuremembers and extending into said anode portion to support said strands,and a tension unit mounted in said chamber, said unit including aplatform and spring assembly surrounding said hangers, a

guiding plate adjacent said tension unit, a tubular sleeve having a slotsupporting said plate on one of said closure members, a tensionadjusting element extending through said sleeve and engaging saidplatform, and means engaging said slot for locking said adjustingelement in a set position.

'7. A high power space current device having a cylindrical metallicanode portion terminated by end insulating portions, a plurality ofleading-in conductors sealed into one of said insulating portions andextendin into said anode portion, a plurality of electron producingstrands joined to said conductors and extending through said anodeportion in coaxial relation thereto, a hollow chamber mounted within theother insulating portion, closure members 0n opposite ends of saidchamber, parallel hanger members passing through said closure membersand extending into said anode portion to support said strands, and atension unit mounted in said chamber, said unit including a platformthrough which said hangers pass, a plurality of gripping elementsengaging said hangers, a plurality of tension springs surrounding saidhangers between said platform and said gripping elements, and springgripping connectors affixing said springs to said platform and saidelements.

8. A high power space current device having a cylindrical metallic anodeportion terminated by end insulating portions, a plurality of leadinginconductors sealed into one of said insulating portions and extendinginto said anode portion, a plurality of electron producing strandsjoined to said conductors and extending through said anode portion, ahollow chamber mounted within the other insulating portion, closuremembers on the opposite ends of said chamber, parallel hanger memberspassing through said closure members and extending into said anodeportion to support said strands, and a tension unit mounted in saidchamber, said unit including a platform through which said hangers pass,a plurality of friction chucks engaging said hangers, a plurality oftension springs surrounding said hangers between said platform and saidchucks, and spring gripping connectors afiixing said springs to saidplatform and to said chucks.

9. A high power space current device having a cylindrical metallic anodeportion terminated by and insulating portions, a plurality of leadinginconductors sealed into one of said insulating portions and extendinginto said anode portion, a plurality of electron producing strandsjoined to said conductors and extending through said anode portion, ahollow chamber mounted within the other insulating portion, closuremembers on the opposite ends of said chamber, parallel hangers passingthrough said closure members and extending into said anode portion tosupport said strands, and a tension unit mounted in said chamber, saidunit including a platform through which said hangers pass, a pluralityof gripping elements engaging said hangers, a plurality of tensionsprings surrounding said hangers between said platform and said grippingelements,

and threaded sleeve members on said platform and said elements,respectively, embracing the ends of said springs to couple said hangersto said platform.

10. A high power space current device comprising a metallic anodeportion and an insulating end portion having a reentrant tubularsection, a dish-type stem sealed to said section having a centralextension projecting toward said anode portion and ferrules projectingin an opposed direction, a plurality of leading-in conductors sealedthrough said ferrules and concentrically arranged about said extension,a guiding mount supported by said extension having apertures spaced inrelation with said ferrules whereby said conductors extend through saidmount, and a plurality of filament strands supported in spaced relationto said anode and connected to said conductors.

11. A high powerspace current device comprising a metallic anode portionand an insulating end portion having a reentrant tubular section, adish-type stem sealed to said section having acentral extensionprojecting towardsaidanode portion and spaced ferrules projecting inanopposeddirection, a plurality of leading-in conductors sealed throughsaid ferrules and concentrically arranged around said extension, aguiding mount supported by said extension having apertures spaced inrelation with said ferrules whereby said conductors insulatingly extendthrough said mount, a plurality of filament strands supported in spacedrelation to said anode and connected to said conductors, and means forconnecting said mount to a conductor.

12. A high power discharge device comprising a metallic anode portion,vitreous portions sealed to opposite ends of the anode portion, afilament supporting assembly coaxially mounted within and by saidvitreous portions, a control electrode interposed between said filamentand said anode portion, a guiding member carried by one of said vitreousportions for one end of said control electrode, an annular membercarried by said other vitreous portion, and tension supporting meansconnecting the other end of said control electrode to said annularmember.

13. A high power space current device having a metallic anode portionand an insualting end portion having a reentrant stem therein, amultistrand filament supported in said anode portion, a plurality ofleading-in conductors for said filament sealed in said stem, an annularinsulating dish stem carried by said insulating end portion adjacentsaid reentrant stem, a cylindrical grid electrode coaxial with saidfilament and said anode and including spaced supports extending towardsaid annular stem, and means including tension springs attaching saidsupports to said annular stem.

14. A high power space current device comprising a metallic anodeportion and an insulating end portion having a reentrant stem therein, amultistrand filament supported in said anode portion, a plurality ofleading-in conductors for said filament sealed in said stem, an annularinsulating stem carried by said insulating end portion adjacent saidreentrant stem, a cylindrical grid coaxial with said filament and saidanode and including spaced supports extending toward said annular stem,segmental ring members attached to pairs of said supports, and pins insaid annular stem engaging said ring members.

15. A double-ended electron discharge power device comprising anexternal anode, glass portions'sealed thereto at opposite ends, areentrant stem in one of said glass portions, a plurality of leading-inconductors sealed in circular formation in said stem, a guiding mounthaving jewel bearings therein secured to said stem, said leading-inconductors slidably extending through said bearings, a hollow insulatingchamber opened at both ends supported in said other glass portion,metallic rings sealed to the open ends of said chamber, aperturedmetallic closure plates affixed to said rings, individual guiding mountssupporting jewel bearings carried by said plates, a plurality ofslidable hangers extending through said bearings and closure plates, atension assembly enclosed in said chamber and including helical springssurrounding said hangers and clamped thereto at an intermediate point, aplurality of filament strands resiliently supported at one end by saidhangers and secured at the other end to said conductors, a cylindricalgrid surrounding said strands, supports on said grid extending into bothglass portions, annular dishtype stems afiixed to said glass portions,said conductors having inlet and outlet air ports formed in said baseconcentric with said conductors for cooling the reentrant stem enclosing10 said conductors.

JAMES E. CLARK. STURE O. EKS-TRAND. VICTOR L. RONCI.

